/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2008, Blender Foundation
 * This is a new part of Blender
 *
 * Contributor(s): Joshua Leung, Antonio Vazquez
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/editors/gpencil/annotate_draw.c
 *  \ingroup edgpencil
 */


#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stddef.h>
#include <math.h>
#include <float.h>

#include "MEM_guardedalloc.h"

#include "BLI_sys_types.h"

#include "BLI_math.h"
#include "BLI_utildefines.h"
#include "BLI_polyfill_2d.h"

#include "BLF_api.h"
#include "BLT_translation.h"

#include "DNA_gpencil_types.h"
#include "DNA_scene_types.h"
#include "DNA_screen_types.h"
#include "DNA_space_types.h"
#include "DNA_view3d_types.h"
#include "DNA_userdef_types.h"
#include "DNA_object_types.h"

#include "BKE_context.h"
#include "BKE_global.h"
#include "BKE_gpencil.h"

#include "WM_api.h"

#include "BIF_glutil.h"

#include "GPU_immediate.h"
#include "GPU_draw.h"
#include "GPU_state.h"

#include "ED_gpencil.h"
#include "ED_screen.h"
#include "ED_view3d.h"
#include "ED_space_api.h"

#include "UI_interface_icons.h"
#include "UI_resources.h"

/* ************************************************** */
/* GREASE PENCIL DRAWING */

/* ----- General Defines ------ */
/* flags for sflag */
typedef enum eDrawStrokeFlags {
	GP_DRAWDATA_NOSTATUS    = (1 << 0),   /* don't draw status info */
	GP_DRAWDATA_ONLY3D      = (1 << 1),   /* only draw 3d-strokes */
	GP_DRAWDATA_ONLYV2D     = (1 << 2),   /* only draw 'canvas' strokes */
	GP_DRAWDATA_ONLYI2D     = (1 << 3),   /* only draw 'image' strokes */
	GP_DRAWDATA_IEDITHACK   = (1 << 4),   /* special hack for drawing strokes in Image Editor (weird coordinates) */
	GP_DRAWDATA_NO_XRAY     = (1 << 5),   /* don't draw xray in 3D view (which is default) */
	GP_DRAWDATA_NO_ONIONS   = (1 << 6),	  /* no onionskins should be drawn (for animation playback) */
} eDrawStrokeFlags;


/* ----- Tool Buffer Drawing ------ */

/* draw stroke defined in buffer (simple ogl lines/points for now, as dotted lines) */
static void gp_draw_stroke_buffer(
        const tGPspoint *points, int totpoints, short thickness,
        short dflag, short sflag, float ink[4])
{
	int draw_points = 0;

	/* error checking */
	if ((points == NULL) || (totpoints <= 0))
		return;

	/* check if buffer can be drawn */
	if (dflag & (GP_DRAWDATA_ONLY3D | GP_DRAWDATA_ONLYV2D))
		return;

	if (sflag & GP_STROKE_ERASER) {
		/* don't draw stroke at all! */
		return;
	}

	GPUVertFormat *format = immVertexFormat();
	uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);

	const tGPspoint *pt = points;

	if (totpoints == 1) {
		/* if drawing a single point, draw it larger */
		GPU_point_size((float)(thickness + 2) * points->pressure);
		immBindBuiltinProgram(GPU_SHADER_3D_POINT_UNIFORM_SIZE_UNIFORM_COLOR_AA);
		immUniformColor3fvAlpha(ink, ink[3]);
		immBegin(GPU_PRIM_POINTS, 1);
		immVertex2fv(pos, &pt->x);
	}
	else {
		float oldpressure = points[0].pressure;

		/* draw stroke curve */
		GPU_line_width(max_ff(oldpressure * thickness, 1.0));

		immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
		immUniformColor3fvAlpha(ink, ink[3]);

		immBeginAtMost(GPU_PRIM_LINE_STRIP, totpoints);

		for (int i = 0; i < totpoints; i++, pt++) {
			/* if there was a significant pressure change, stop the curve, change the thickness of the stroke,
			 * and continue drawing again (since line-width cannot change in middle of GL_LINE_STRIP)
			 */
			if (fabsf(pt->pressure - oldpressure) > 0.2f) {
				/* need to have 2 points to avoid immEnd assert error */
				if (draw_points < 2) {
					immVertex2fv(pos, &(pt - 1)->x);
				}

				immEnd();
				draw_points = 0;

				GPU_line_width(max_ff(pt->pressure * thickness, 1.0f));
				immBeginAtMost(GPU_PRIM_LINE_STRIP, totpoints - i + 1);

				/* need to roll-back one point to ensure that there are no gaps in the stroke */
				if (i != 0) {
					immVertex2fv(pos, &(pt - 1)->x);
					draw_points++;
				}

				oldpressure = pt->pressure; /* reset our threshold */
			}

			/* now the point we want */
			immVertex2fv(pos, &pt->x);
			draw_points++;
		}
		/* need to have 2 points to avoid immEnd assert error */
		if (draw_points < 2) {
			immVertex2fv(pos, &(pt - 1)->x);
		}
	}

	immEnd();
	immUnbindProgram();
}

/* --------- 2D Stroke Drawing Helpers --------- */
/* change in parameter list */
static void gp_calc_2d_stroke_fxy(const float pt[3], short sflag, int offsx, int offsy, int winx, int winy, float r_co[2])
{
	if (sflag & GP_STROKE_2DSPACE) {
		r_co[0] = pt[0];
		r_co[1] = pt[1];
	}
	else if (sflag & GP_STROKE_2DIMAGE) {
		const float x = (float)((pt[0] * winx) + offsx);
		const float y = (float)((pt[1] * winy) + offsy);

		r_co[0] = x;
		r_co[1] = y;
	}
	else {
		const float x = (float)(pt[0] / 100 * winx) + offsx;
		const float y = (float)(pt[1] / 100 * winy) + offsy;

		r_co[0] = x;
		r_co[1] = y;
	}
}

/* ----- Existing Strokes Drawing (3D and Point) ------ */

/* draw a given stroke - just a single dot (only one point) */
static void gp_draw_stroke_point(
        const bGPDspoint *points, short thickness, short UNUSED(dflag), short sflag,
        int offsx, int offsy, int winx, int winy, const float ink[4])
{
	const bGPDspoint *pt = points;

	/* get final position using parent matrix */
	float fpt[3];
	copy_v3_v3(fpt, &pt->x);

	GPUVertFormat *format = immVertexFormat();
	uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);

	if (sflag & GP_STROKE_3DSPACE) {
		immBindBuiltinProgram(GPU_SHADER_3D_POINT_UNIFORM_SIZE_UNIFORM_COLOR_AA);
	}
	else {
		immBindBuiltinProgram(GPU_SHADER_2D_POINT_UNIFORM_SIZE_UNIFORM_COLOR_AA);

		/* get 2D coordinates of point */
		float co[3] = { 0.0f };
		gp_calc_2d_stroke_fxy(fpt, sflag, offsx, offsy, winx, winy, co);
		copy_v3_v3(fpt, co);
	}

	/* set color */
	immUniformColor3fvAlpha(ink, ink[3]);

	/* set point thickness (since there's only one of these) */
	immUniform1f("size", (float)(thickness + 2) * pt->pressure);

	immBegin(GPU_PRIM_POINTS, 1);
	immVertex3fv(pos, fpt);
	immEnd();

	immUnbindProgram();
}

/* draw a given stroke in 3d (i.e. in 3d-space), using simple ogl lines */
static void gp_draw_stroke_3d(
        const bGPDspoint *points, int totpoints, short thickness,
        short UNUSED(sflag), const float ink[4], bool cyclic)
{
	float curpressure = points[0].pressure;
	float cyclic_fpt[3];
	int draw_points = 0;

	/* if cyclic needs one vertex more */
	int cyclic_add = 0;
	if (cyclic) {
		cyclic_add++;
	}


	GPUVertFormat *format = immVertexFormat();
	uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);

	immBindBuiltinProgram(GPU_SHADER_3D_UNIFORM_COLOR);
	immUniformColor3fvAlpha(ink, ink[3]);

	/* draw stroke curve */
	GPU_line_width(max_ff(curpressure * thickness, 1.0f));
	immBeginAtMost(GPU_PRIM_LINE_STRIP, totpoints + cyclic_add);
	const bGPDspoint *pt = points;
	for (int i = 0; i < totpoints; i++, pt++) {
		/* if there was a significant pressure change, stop the curve, change the thickness of the stroke,
		 * and continue drawing again (since line-width cannot change in middle of GL_LINE_STRIP)
		 * Note: we want more visible levels of pressures when thickness is bigger.
		 */
		if (fabsf(pt->pressure - curpressure) > 0.2f / (float)thickness) {
			/* if the pressure changes before get at least 2 vertices, need to repeat last point to avoid assert in immEnd() */
			if (draw_points < 2) {
				const bGPDspoint *pt2 = pt - 1;
				immVertex3fv(pos, &pt2->x);
			}
			immEnd();
			draw_points = 0;

			curpressure = pt->pressure;
			GPU_line_width(max_ff(curpressure * thickness, 1.0f));
			immBeginAtMost(GPU_PRIM_LINE_STRIP, totpoints - i + 1 + cyclic_add);

			/* need to roll-back one point to ensure that there are no gaps in the stroke */
			if (i != 0) {
				const bGPDspoint *pt2 = pt - 1;
				immVertex3fv(pos, &pt2->x);
				draw_points++;
			}
		}

		/* now the point we want */
		immVertex3fv(pos, &pt->x);
		draw_points++;

		if (cyclic && i == 0) {
			/* save first point to use in cyclic */
			copy_v3_v3(cyclic_fpt, &pt->x);
		}
	}

	if (cyclic) {
		/* draw line to first point to complete the cycle */
		immVertex3fv(pos, cyclic_fpt);
		draw_points++;
	}

	/* if less of two points, need to repeat last point to avoid assert in immEnd() */
	if (draw_points < 2) {
		const bGPDspoint *pt2 = pt - 1;
		immVertex3fv(pos, &pt2->x);
	}

	immEnd();
	immUnbindProgram();
}

/* ----- Fancy 2D-Stroke Drawing ------ */

/* draw a given stroke in 2d */
static void gp_draw_stroke_2d(
        const bGPDspoint *points, int totpoints, short thickness_s, short dflag, short sflag,
        int offsx, int offsy, int winx, int winy, const float ink[4])
{
	/* otherwise thickness is twice that of the 3D view */
	float thickness = (float)thickness_s * 0.5f;

	/* strokes in Image Editor need a scale factor, since units there are not pixels! */
	float scalefac  = 1.0f;
	if ((dflag & GP_DRAWDATA_IEDITHACK) && (dflag & GP_DRAWDATA_ONLYV2D)) {
		scalefac = 0.001f;
	}

	/* tessellation code - draw stroke as series of connected quads (triangle strips in fact) with connection
	 * edges rotated to minimize shrinking artifacts, and rounded endcaps
	 */
	{
		const bGPDspoint *pt1, *pt2;
		float s0[2], s1[2];     /* segment 'center' points */
		float pm[2];  /* normal from previous segment. */
		int i;

		GPUVertFormat *format = immVertexFormat();
		uint pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);

		immBindBuiltinProgram(GPU_SHADER_2D_UNIFORM_COLOR);
		immUniformColor3fvAlpha(ink, ink[3]);
		immBegin(GPU_PRIM_TRI_STRIP, totpoints * 2 + 4);

		/* get x and y coordinates from first point */
		gp_calc_2d_stroke_fxy(&points->x, sflag, offsx, offsy, winx, winy, s0);

		for (i = 0, pt1 = points, pt2 = points + 1; i < (totpoints - 1); i++, pt1++, pt2++) {
			float t0[2], t1[2];     /* tessellated coordinates */
			float m1[2], m2[2];     /* gradient and normal */
			float mt[2], sc[2];     /* gradient for thickness, point for end-cap */
			float pthick;           /* thickness at segment point */

			/* get x and y coordinates from point2 (point1 has already been computed in previous iteration). */
			gp_calc_2d_stroke_fxy(&pt2->x, sflag, offsx, offsy, winx, winy, s1);

			/* calculate gradient and normal - 'angle'=(ny/nx) */
			m1[1] = s1[1] - s0[1];
			m1[0] = s1[0] - s0[0];
			normalize_v2(m1);
			m2[1] = -m1[0];
			m2[0] = m1[1];

			/* always use pressure from first point here */
			pthick = (pt1->pressure * thickness * scalefac);

			/* if the first segment, start of segment is segment's normal */
			if (i == 0) {
				/* draw start cap first
				 * - make points slightly closer to center (about halfway across)
				 */
				mt[0] = m2[0] * pthick * 0.5f;
				mt[1] = m2[1] * pthick * 0.5f;
				sc[0] = s0[0] - (m1[0] * pthick * 0.75f);
				sc[1] = s0[1] - (m1[1] * pthick * 0.75f);

				t0[0] = sc[0] - mt[0];
				t0[1] = sc[1] - mt[1];
				t1[0] = sc[0] + mt[0];
				t1[1] = sc[1] + mt[1];

				/* First two points of cap. */
				immVertex2fv(pos, t0);
				immVertex2fv(pos, t1);

				/* calculate points for start of segment */
				mt[0] = m2[0] * pthick;
				mt[1] = m2[1] * pthick;

				t0[0] = s0[0] - mt[0];
				t0[1] = s0[1] - mt[1];
				t1[0] = s0[0] + mt[0];
				t1[1] = s0[1] + mt[1];

				/* Last two points of start cap (and first two points of first segment). */
				immVertex2fv(pos, t0);
				immVertex2fv(pos, t1);
			}
			/* if not the first segment, use bisector of angle between segments */
			else {
				float mb[2];         /* bisector normal */
				float athick, dfac;  /* actual thickness, difference between thicknesses */

				/* calculate gradient of bisector (as average of normals) */
				mb[0] = (pm[0] + m2[0]) / 2;
				mb[1] = (pm[1] + m2[1]) / 2;
				normalize_v2(mb);

				/* calculate gradient to apply
				 *  - as basis, use just pthick * bisector gradient
				 * - if cross-section not as thick as it should be, add extra padding to fix it
				 */
				mt[0] = mb[0] * pthick;
				mt[1] = mb[1] * pthick;
				athick = len_v2(mt);
				dfac = pthick - (athick * 2);

				if (((athick * 2.0f) < pthick) && (IS_EQF(athick, pthick) == 0)) {
					mt[0] += (mb[0] * dfac);
					mt[1] += (mb[1] * dfac);
				}

				/* calculate points for start of segment */
				t0[0] = s0[0] - mt[0];
				t0[1] = s0[1] - mt[1];
				t1[0] = s0[0] + mt[0];
				t1[1] = s0[1] + mt[1];

				/* Last two points of previous segment, and first two points of current segment. */
				immVertex2fv(pos, t0);
				immVertex2fv(pos, t1);
			}

			/* if last segment, also draw end of segment (defined as segment's normal) */
			if (i == totpoints - 2) {
				/* for once, we use second point's pressure (otherwise it won't be drawn) */
				pthick = (pt2->pressure * thickness * scalefac);

				/* calculate points for end of segment */
				mt[0] = m2[0] * pthick;
				mt[1] = m2[1] * pthick;

				t0[0] = s1[0] - mt[0];
				t0[1] = s1[1] - mt[1];
				t1[0] = s1[0] + mt[0];
				t1[1] = s1[1] + mt[1];

				/* Last two points of last segment (and first two points of end cap). */
				immVertex2fv(pos, t0);
				immVertex2fv(pos, t1);

				/* draw end cap as last step
				 * - make points slightly closer to center (about halfway across)
				 */
				mt[0] = m2[0] * pthick * 0.5f;
				mt[1] = m2[1] * pthick * 0.5f;
				sc[0] = s1[0] + (m1[0] * pthick * 0.75f);
				sc[1] = s1[1] + (m1[1] * pthick * 0.75f);

				t0[0] = sc[0] - mt[0];
				t0[1] = sc[1] - mt[1];
				t1[0] = sc[0] + mt[0];
				t1[1] = sc[1] + mt[1];

				/* Last two points of end cap. */
				immVertex2fv(pos, t0);
				immVertex2fv(pos, t1);
			}

			/* store computed point2 coordinates as point1 ones of next segment. */
			copy_v2_v2(s0, s1);
			/* store stroke's 'natural' normal for next stroke to use */
			copy_v2_v2(pm, m2);
		}

		immEnd();
		immUnbindProgram();
	}
}

/* ----- Strokes Drawing ------ */

/* Helper for doing all the checks on whether a stroke can be drawn */
static bool gp_can_draw_stroke(const bGPDstroke *gps, const int dflag)
{
	/* skip stroke if it isn't in the right display space for this drawing context */
	/* 1) 3D Strokes */
	if ((dflag & GP_DRAWDATA_ONLY3D) && !(gps->flag & GP_STROKE_3DSPACE))
		return false;
	if (!(dflag & GP_DRAWDATA_ONLY3D) && (gps->flag & GP_STROKE_3DSPACE))
		return false;

	/* 2) Screen Space 2D Strokes */
	if ((dflag & GP_DRAWDATA_ONLYV2D) && !(gps->flag & GP_STROKE_2DSPACE))
		return false;
	if (!(dflag & GP_DRAWDATA_ONLYV2D) && (gps->flag & GP_STROKE_2DSPACE))
		return false;

	/* 3) Image Space (2D) */
	if ((dflag & GP_DRAWDATA_ONLYI2D) && !(gps->flag & GP_STROKE_2DIMAGE))
		return false;
	if (!(dflag & GP_DRAWDATA_ONLYI2D) && (gps->flag & GP_STROKE_2DIMAGE))
		return false;

	/* skip stroke if it doesn't have any valid data */
	if ((gps->points == NULL) || (gps->totpoints < 1))
		return false;

	/* stroke can be drawn */
	return true;
}

/* draw a set of strokes */
static void gp_draw_strokes(
        bGPdata *UNUSED(gpd), bGPDlayer *UNUSED(gpl), const bGPDframe *gpf, int offsx, int offsy, int winx, int winy,
        int dflag, short lthick, const float color[4])
{
	GPU_enable_program_point_size();

	for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
		/* check if stroke can be drawn */
		if (gp_can_draw_stroke(gps, dflag) == false) {
			continue;
		}

		/* check which stroke-drawer to use */
		if (dflag & GP_DRAWDATA_ONLY3D) {
			const int no_xray = (dflag & GP_DRAWDATA_NO_XRAY);
			int mask_orig = 0;

			if (no_xray) {
				glGetIntegerv(GL_DEPTH_WRITEMASK, &mask_orig);
				glDepthMask(0);
				GPU_depth_test(true);

				/* first arg is normally rv3d->dist, but this isn't
				 * available here and seems to work quite well without */
				bglPolygonOffset(1.0f, 1.0f);
			}

			/* 3D Lines - OpenGL primitives-based */
			if (gps->totpoints == 1) {
				gp_draw_stroke_point(gps->points, lthick, dflag, gps->flag, offsx, offsy, winx, winy, color);
			}
			else {
				gp_draw_stroke_3d(
				        gps->points, gps->totpoints, lthick, gps->flag,
				        color, gps->flag & GP_STROKE_CYCLIC);
			}

			if (no_xray) {
				glDepthMask(mask_orig);
				GPU_depth_test(false);

				bglPolygonOffset(0.0, 0.0);
			}
		}
		else {
			/* 2D Strokes... */
			if (gps->totpoints == 1) {
				gp_draw_stroke_point(gps->points, lthick, dflag, gps->flag, offsx, offsy, winx, winy, color);
			}
			else {
				gp_draw_stroke_2d(
				        gps->points, gps->totpoints, lthick, dflag, gps->flag,
				        offsx, offsy, winx, winy, color);
			}
		}
	}

	GPU_disable_program_point_size();
}

/* Draw selected verts for strokes being edited */
static void gp_draw_strokes_edit(
        bGPdata *gpd, bGPDlayer *gpl, const bGPDframe *gpf,
        int offsx, int offsy, int winx, int winy,
        short dflag, short UNUSED(lflag), float alpha)
{
	/* if alpha 0 do not draw */
	if (alpha == 0.0f)
		return;

	const bool no_xray = (dflag & GP_DRAWDATA_NO_XRAY) != 0;
	int mask_orig = 0;

	/* set up depth masks... */
	if (dflag & GP_DRAWDATA_ONLY3D) {
		if (no_xray) {
			glGetIntegerv(GL_DEPTH_WRITEMASK, &mask_orig);
			glDepthMask(0);
			GPU_depth_test(true);

			/* first arg is normally rv3d->dist, but this isn't
			 * available here and seems to work quite well without */
			bglPolygonOffset(1.0f, 1.0f);
		}
	}

	GPU_enable_program_point_size();

	/* draw stroke verts */
	for (bGPDstroke *gps = gpf->strokes.first; gps; gps = gps->next) {
		/* check if stroke can be drawn */
		if (gp_can_draw_stroke(gps, dflag) == false)
			continue;

		/* Optimisation: only draw points for selected strokes
		 * We assume that selected points can only occur in
		 * strokes that are selected too.
		 */
		if ((gps->flag & GP_STROKE_SELECT) == 0)
			continue;

		/* Get size of verts:
		 * - The selected state needs to be larger than the unselected state so that
		 *   they stand out more.
		 * - We use the theme setting for size of the unselected verts
		 */
		float bsize = UI_GetThemeValuef(TH_GP_VERTEX_SIZE);
		float vsize;
		if ((int)bsize > 8) {
			vsize = 10.0f;
			bsize = 8.0f;
		}
		else {
			vsize = bsize + 2;
		}

		float selectColor[4];
		UI_GetThemeColor3fv(TH_GP_VERTEX_SELECT, selectColor);
		selectColor[3] = alpha;

		GPUVertFormat *format = immVertexFormat();
		uint pos; /* specified later */
		uint size = GPU_vertformat_attr_add(format, "size", GPU_COMP_F32, 1, GPU_FETCH_FLOAT);
		uint color = GPU_vertformat_attr_add(format, "color", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);

		if (gps->flag & GP_STROKE_3DSPACE) {
			pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 3, GPU_FETCH_FLOAT);
			immBindBuiltinProgram(GPU_SHADER_3D_POINT_VARYING_SIZE_VARYING_COLOR);
		}
		else {
			pos = GPU_vertformat_attr_add(format, "pos", GPU_COMP_F32, 2, GPU_FETCH_FLOAT);
			immBindBuiltinProgram(GPU_SHADER_2D_POINT_VARYING_SIZE_VARYING_COLOR);
		}

		immBegin(GPU_PRIM_POINTS, gps->totpoints);

		/* Draw start and end point differently if enabled stroke direction hint */
		bool show_direction_hint = (gpd->flag & GP_DATA_SHOW_DIRECTION) && (gps->totpoints > 1);

		/* Draw all the stroke points (selected or not) */
		bGPDspoint *pt = gps->points;
		for (int i = 0; i < gps->totpoints; i++, pt++) {
			/* size and color first */
			if (show_direction_hint && i == 0) {
				/* start point in green bigger */
				immAttr3f(color, 0.0f, 1.0f, 0.0f);
				immAttr1f(size, vsize + 4);
			}
			else if (show_direction_hint && (i == gps->totpoints - 1)) {
				/* end point in red smaller */
				immAttr3f(color, 1.0f, 0.0f, 0.0f);
				immAttr1f(size, vsize + 1);
			}
			else if (pt->flag & GP_SPOINT_SELECT) {
				immAttr3fv(color, selectColor);
				immAttr1f(size, vsize);
			}
			else {
				immAttr3fv(color, gpl->color);
				immAttr1f(size, bsize);
			}

			/* then position */
			if (gps->flag & GP_STROKE_3DSPACE) {
				immVertex3fv(pos, &pt->x);
			}
			else {
				float co[2];
				gp_calc_2d_stroke_fxy(&pt->x, gps->flag, offsx, offsy, winx, winy, co);
				immVertex2fv(pos, co);
			}
		}

		immEnd();
		immUnbindProgram();
	}

	GPU_disable_program_point_size();

	/* clear depth mask */
	if (dflag & GP_DRAWDATA_ONLY3D) {
		if (no_xray) {
			glDepthMask(mask_orig);
			GPU_depth_test(false);

			bglPolygonOffset(0.0, 0.0);
#if 0
			glDisable(GL_POLYGON_OFFSET_LINE);
			glPolygonOffset(0, 0);
#endif
		}
	}
}

/* ----- General Drawing ------ */
/* draw onion-skinning for a layer */
static void gp_draw_onionskins(
	bGPdata *gpd, bGPDlayer *gpl, bGPDframe *gpf, int offsx, int offsy, int winx, int winy,
	int UNUSED(cfra), int dflag)
{
	const float alpha = 1.0f;
	float color[4];

	/* 1) Draw Previous Frames First */
	copy_v3_v3(color, gpl->gcolor_prev);

	if (gpl->gstep > 0) {
		bGPDframe *gf;
		float fac;

		/* draw previous frames first */
		for (gf = gpf->prev; gf; gf = gf->prev) {
			/* check if frame is drawable */
			if ((gpf->framenum - gf->framenum) <= gpl->gstep) {
				/* alpha decreases with distance from curframe index */
				fac = 1.0f - ((float)(gpf->framenum - gf->framenum) / (float)(gpl->gstep + 1));
				color[3] = alpha * fac * 0.66f;
				gp_draw_strokes(
					gpd, gpl, gf, offsx, offsy, winx, winy, dflag,
					gpl->thickness, color);
			}
			else
				break;
		}
	}
	else if (gpl->gstep == 0) {
		/* draw the strokes for the ghost frames (at half of the alpha set by user) */
		if (gpf->prev) {
			color[3] = (alpha / 7);
			gp_draw_strokes(
				gpd, gpl, gpf->prev, offsx, offsy, winx, winy, dflag,
				gpl->thickness, color);
		}
	}
	else {
		/* don't draw - disabled */
	}


	/* 2) Now draw next frames */
	copy_v3_v3(color, gpl->gcolor_next);

	if (gpl->gstep_next > 0) {
		bGPDframe *gf;
		float fac;

		/* now draw next frames */
		for (gf = gpf->next; gf; gf = gf->next) {
			/* check if frame is drawable */
			if ((gf->framenum - gpf->framenum) <= gpl->gstep_next) {
				/* alpha decreases with distance from curframe index */
				fac = 1.0f - ((float)(gf->framenum - gpf->framenum) / (float)(gpl->gstep_next + 1));
				color[3] = alpha * fac * 0.66f;
				gp_draw_strokes(
					gpd, gpl, gf, offsx, offsy, winx, winy, dflag,
					gpl->thickness, color);
			}
			else
				break;
		}
	}
	else if (gpl->gstep_next == 0) {
		/* draw the strokes for the ghost frames (at half of the alpha set by user) */
		if (gpf->next) {
			color[3] = (alpha / 4);
			gp_draw_strokes(
				gpd, gpl, gpf->next, offsx, offsy, winx, winy, dflag,
				gpl->thickness, color);
		}
	}
	else {
		/* don't draw - disabled */
	}

}

/* loop over gpencil data layers, drawing them */
static void gp_draw_data_layers(
        bGPdata *gpd, int offsx, int offsy, int winx, int winy,
        int cfra, int dflag, float alpha)
{
	float ink[4];

	for (bGPDlayer *gpl = gpd->layers.first; gpl; gpl = gpl->next) {
		/* verify never thickness is less than 1 */
		CLAMP_MIN(gpl->thickness, 1.0f);
		short lthick = gpl->thickness;

		/* apply layer opacity */
		copy_v3_v3(ink, gpl->color);
		ink[3] = gpl->opacity;

		/* don't draw layer if hidden */
		if (gpl->flag & GP_LAYER_HIDE)
			continue;

		/* get frame to draw */
		bGPDframe *gpf = BKE_gpencil_layer_getframe(gpl, cfra, GP_GETFRAME_USE_PREV);
		if (gpf == NULL)
			continue;

		/* set basic stroke thickness */
		GPU_line_width(lthick);

		/* Add layer drawing settings to the set of "draw flags"
		 * NOTE: If the setting doesn't apply, it *must* be cleared,
		 *       as dflag's carry over from the previous layer
		 */

		/* xray... */
		SET_FLAG_FROM_TEST(dflag, gpl->flag & GP_LAYER_NO_XRAY, GP_DRAWDATA_NO_XRAY);

		/* Draw 'onionskins' (frame left + right) */
		if (gpl->onion_flag & GP_LAYER_ONIONSKIN) {
			gp_draw_onionskins(gpd, gpl, gpf, offsx, offsy, winx, winy, cfra, dflag);
		}

		/* draw the strokes already in active frame */
		gp_draw_strokes(gpd, gpl, gpf, offsx, offsy, winx, winy, dflag, lthick, ink);

		/* Draw verts of selected strokes
		 *  - when doing OpenGL renders, we don't want to be showing these, as that ends up flickering
		 *  - locked layers can't be edited, so there's no point showing these verts
		 *    as they will have no bearings on what gets edited
		 *  - only show when in editmode, since operators shouldn't work otherwise
		 *    (NOTE: doing it this way means that the toggling editmode shows visible change immediately)
		 */
		/* XXX: perhaps we don't want to show these when users are drawing... */
		if ((G.f & G_RENDER_OGL) == 0 &&
		    (gpl->flag & GP_LAYER_LOCKED) == 0 &&
		    (gpd->flag & GP_DATA_STROKE_EDITMODE))
		{
			gp_draw_strokes_edit(gpd, gpl, gpf, offsx, offsy, winx, winy, dflag, gpl->flag, alpha);
		}

		/* Check if may need to draw the active stroke cache, only if this layer is the active layer
		 * that is being edited. (Stroke buffer is currently stored in gp-data)
		 */
		if (ED_gpencil_session_active() && (gpl->flag & GP_LAYER_ACTIVE) &&
		    (gpf->flag & GP_FRAME_PAINT))
		{
			/* Buffer stroke needs to be drawn with a different linestyle
			 * to help differentiate them from normal strokes.
			 *
			 * It should also be noted that sbuffer contains temporary point types
			 * i.e. tGPspoints NOT bGPDspoints
			 */
			gp_draw_stroke_buffer(
			        gpd->runtime.sbuffer,
			        gpd->runtime.sbuffer_size, lthick,
			        dflag, gpd->runtime.sbuffer_sflag, ink);
		}
	}
}

/* draw a short status message in the top-right corner */
static void gp_draw_status_text(const bGPdata *gpd, ARegion *ar)
{
	rcti rect;

	/* Cannot draw any status text when drawing OpenGL Renders */
	if (G.f & G_RENDER_OGL)
		return;

	/* Get bounds of region - Necessary to avoid problems with region overlap */
	ED_region_visible_rect(ar, &rect);

	/* for now, this should only be used to indicate when we are in stroke editmode */
	if (gpd->flag & GP_DATA_STROKE_EDITMODE) {
		const char *printable = IFACE_("GPencil Stroke Editing");
		float       printable_size[2];

		int font_id = BLF_default();

		BLF_width_and_height(font_id, printable, BLF_DRAW_STR_DUMMY_MAX, &printable_size[0], &printable_size[1]);

		int xco = (rect.xmax - U.widget_unit) - (int)printable_size[0];
		int yco = (rect.ymax - U.widget_unit);

		/* text label */
		UI_FontThemeColor(font_id, TH_TEXT_HI);
#ifdef WITH_INTERNATIONAL
		BLF_draw_default(xco, yco, 0.0f, printable, BLF_DRAW_STR_DUMMY_MAX);
#else
		BLF_draw_default_ascii(xco, yco, 0.0f, printable, BLF_DRAW_STR_DUMMY_MAX);
#endif

		/* grease pencil icon... */
		// XXX: is this too intrusive?
		GPU_blend_set_func_separate(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA, GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
		GPU_blend(true);

		xco -= U.widget_unit;
		yco -= (int)printable_size[1] / 2;

		UI_icon_draw(xco, yco, ICON_GREASEPENCIL);

		GPU_blend(false);
	}
}

/* draw grease-pencil datablock */
static void gp_draw_data(
        bGPdata *gpd, int offsx, int offsy, int winx, int winy,
        int cfra, int dflag, float alpha)
{
	/* turn on smooth lines (i.e. anti-aliasing) */
	GPU_line_smooth(true);

	/* turn on alpha-blending */
	GPU_blend_set_func_separate(GPU_SRC_ALPHA, GPU_ONE_MINUS_SRC_ALPHA, GPU_ONE, GPU_ONE_MINUS_SRC_ALPHA);
	GPU_blend(true);

	/* draw! */
	gp_draw_data_layers(gpd, offsx, offsy, winx, winy, cfra, dflag, alpha);

	/* turn off alpha blending, then smooth lines */
	GPU_blend(false); // alpha blending
	GPU_line_smooth(false); // smooth lines
}

/* if we have strokes for scenes (3d view)/clips (movie clip editor)
 * and objects/tracks, multiple data blocks have to be drawn */
static void gp_draw_data_all(
        Scene *scene, bGPdata *gpd, int offsx, int offsy, int winx, int winy,
        int cfra, int dflag, const char spacetype)
{
	bGPdata *gpd_source = NULL;
	float alpha = 1.0f;

	if (scene) {
		if (spacetype == SPACE_VIEW3D) {
			gpd_source = (scene->gpd ? scene->gpd : NULL);
		}
		else if (spacetype == SPACE_CLIP && scene->clip) {
			/* currently drawing only gpencil data from either clip or track, but not both - XXX fix logic behind */
			gpd_source = (scene->clip->gpd ? scene->clip->gpd : NULL);
		}

		if (gpd_source) {
			gp_draw_data(gpd_source, offsx, offsy, winx, winy, cfra, dflag, alpha);
		}
	}

	/* scene/clip data has already been drawn, only object/track data is drawn here
	 * if gpd_source == gpd, we don't have any object/track data and we can skip */
	if (gpd_source == NULL || (gpd_source && gpd_source != gpd)) {
		gp_draw_data(gpd, offsx, offsy, winx, winy, cfra, dflag, alpha);
	}
}

/* ----- Grease Pencil Sketches Drawing API ------ */

/* ............................
 * XXX
 * We need to review the calls below, since they may be/are not that suitable for
 * the new ways that we intend to be drawing data...
 * ............................ */

/* draw grease-pencil sketches to specified 2d-view that uses ibuf corrections */
void ED_gpencil_draw_2dimage(const bContext *C)
{
	wmWindowManager *wm = CTX_wm_manager(C);
	ScrArea *sa = CTX_wm_area(C);
	ARegion *ar = CTX_wm_region(C);
	Scene *scene = CTX_data_scene(C);

	int offsx, offsy, sizex, sizey;
	int dflag = GP_DRAWDATA_NOSTATUS;

	bGPdata *gpd = ED_gpencil_data_get_active(C); // XXX
	if (gpd == NULL) return;

	/* calculate rect */
	switch (sa->spacetype) {
		case SPACE_IMAGE: /* image */
		case SPACE_CLIP: /* clip */
		{
			/* just draw using standard scaling (settings here are currently ignored anyways) */
			/* FIXME: the opengl poly-strokes don't draw at right thickness when done this way, so disabled */
			offsx = 0;
			offsy = 0;
			sizex = ar->winx;
			sizey = ar->winy;

			wmOrtho2(ar->v2d.cur.xmin, ar->v2d.cur.xmax, ar->v2d.cur.ymin, ar->v2d.cur.ymax);

			dflag |= GP_DRAWDATA_ONLYV2D | GP_DRAWDATA_IEDITHACK;
			break;
		}
		case SPACE_SEQ: /* sequence */
		{
			/* just draw using standard scaling (settings here are currently ignored anyways) */
			offsx = 0;
			offsy = 0;
			sizex = ar->winx;
			sizey = ar->winy;

			/* NOTE: I2D was used in 2.4x, but the old settings for that have been deprecated
			 * and everything moved to standard View2d
			 */
			dflag |= GP_DRAWDATA_ONLYV2D;
			break;
		}
		default: /* for spacetype not yet handled */
			offsx = 0;
			offsy = 0;
			sizex = ar->winx;
			sizey = ar->winy;

			dflag |= GP_DRAWDATA_ONLYI2D;
			break;
	}

	if (ED_screen_animation_playing(wm)) {
		/* don't show onionskins during animation playback/scrub (i.e. it obscures the poses)
		 * OpenGL Renders (i.e. final output), or depth buffer (i.e. not real strokes)
		 */
		dflag |= GP_DRAWDATA_NO_ONIONS;
	}

	/* draw it! */
	gp_draw_data_all(scene, gpd, offsx, offsy, sizex, sizey, CFRA, dflag, sa->spacetype);
}

/* draw grease-pencil sketches to specified 2d-view assuming that matrices are already set correctly
 * Note: this gets called twice - first time with onlyv2d=true to draw 'canvas' strokes,
 * second time with onlyv2d=false for screen-aligned strokes */
void ED_gpencil_draw_view2d(const bContext *C, bool onlyv2d)
{
	wmWindowManager *wm = CTX_wm_manager(C);
	ScrArea *sa = CTX_wm_area(C);
	ARegion *ar = CTX_wm_region(C);
	Scene *scene = CTX_data_scene(C);
	int dflag = 0;

	/* check that we have grease-pencil stuff to draw */
	if (sa == NULL) return;
	bGPdata *gpd = ED_gpencil_data_get_active(C); // XXX
	if (gpd == NULL) return;

	/* special hack for Image Editor */
	/* FIXME: the opengl poly-strokes don't draw at right thickness when done this way, so disabled */
	if (ELEM(sa->spacetype, SPACE_IMAGE, SPACE_CLIP))
		dflag |= GP_DRAWDATA_IEDITHACK;

	/* draw it! */
	if (onlyv2d) dflag |= (GP_DRAWDATA_ONLYV2D | GP_DRAWDATA_NOSTATUS);
	if (ED_screen_animation_playing(wm)) dflag |= GP_DRAWDATA_NO_ONIONS;

	gp_draw_data_all(scene, gpd, 0, 0, ar->winx, ar->winy, CFRA, dflag, sa->spacetype);

	/* draw status text (if in screen/pixel-space) */
	if (!onlyv2d) {
		gp_draw_status_text(gpd, ar);
	}
}


/* draw annotations sketches to specified 3d-view assuming that matrices are already set correctly
 * Note: this gets called twice - first time with only3d=true to draw 3d-strokes,
 * second time with only3d=false for screen-aligned strokes */
void ED_gpencil_draw_view3d_annotations(
        Scene *scene, struct Depsgraph *depsgraph,
        View3D *v3d, ARegion *ar,
        bool only3d)
{
	int dflag = 0;
	RegionView3D *rv3d = ar->regiondata;
	int offsx,  offsy,  winx,  winy;

	/* check that we have grease-pencil stuff to draw */
	/* XXX: Hardcoded reference here may get out of sync if we change how we fetch annotation data */
	bGPdata *gpd = scene->gpd;
	if (gpd == NULL) return;

	/* when rendering to the offscreen buffer we don't want to
	 * deal with the camera border, otherwise map the coords to the camera border. */
	if ((rv3d->persp == RV3D_CAMOB) && !(G.f & G_RENDER_OGL)) {
		rctf rectf;
		ED_view3d_calc_camera_border(scene, depsgraph, ar, v3d, rv3d, &rectf, true); /* no shift */

		offsx = round_fl_to_int(rectf.xmin);
		offsy = round_fl_to_int(rectf.ymin);
		winx  = round_fl_to_int(rectf.xmax - rectf.xmin);
		winy  = round_fl_to_int(rectf.ymax - rectf.ymin);
	}
	else {
		offsx = 0;
		offsy = 0;
		winx  = ar->winx;
		winy  = ar->winy;
	}

	/* set flags */
	if (only3d) {
		/* 3D strokes/3D space:
		 * - only 3D space points
		 * - don't status text either (as it's the wrong space)
		 */
		dflag |= (GP_DRAWDATA_ONLY3D | GP_DRAWDATA_NOSTATUS);
	}

	if (v3d->flag2 & V3D_RENDER_OVERRIDE) {
		/* don't draw status text when "only render" flag is set */
		dflag |= GP_DRAWDATA_NOSTATUS;
	}

	/* draw it! */
	gp_draw_data_all(scene, gpd, offsx, offsy, winx, winy, CFRA, dflag, v3d->spacetype);
}

/* ************************************************** */
